Screw and nut driving devices, which incorporate ball or roller nuts, i.e. where balls or rollers recirculate in grooves constituted by the nut and screw threads, have so small friction losses that they are not irreversible. Small friction losses are, of course, desirable from energy aspects, but non-irreversible devices are inappropriate from safety aspects in certain connections, e.g. in lifting devices. Different blocking and braking arrangements have earlier been proposed for solving this problem. They generally have been arranged in connection to the driving motor and they have locked or braked the output shaft of the motor, often in dependency of the energy supply to the motor, which is generally arranged for driving the screw thus that the nut without rotation is displaced along the screw, when this rotates. Rotation of the screw is, however, non-appropriate at rapid approach, as a long and slender screw ought to rotate at a lower speed than its critical speed. Locking and braking means between the motor and the screw increase the dimension of the device.